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    <div class="header">
      <h1>D2RQ</h1>
      <div id="subtitle">Accessing Relational Databases<br />as Virtual RDF Graphs</div>
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<div class="nav home">
  <ul>
    <li class="group"><span><strong>Download</strong></span>
      <ul>
        <li><a href="https://github.com/downloads/d2rq/d2rq/d2rq-0.8.1.zip">d2rq-0.8.1.zip</a></li>
        <li class="last"><a href="https://github.com/downloads/d2rq/d2rq/d2rq-0.8.1.tar.gz">d2rq-0.8.1.tar.gz</a></li>
      </ul>
    </li>
    <li><a href="getting-started">Getting Started</a></li>
    <li><a href="d2rq-language">D2RQ Mapping Language</a></li>
    <li class="group"><span>Tools</span>
      <ul>
        <li><a href="d2r-server">D2R Server</a></li>
        <li><a href="generate-mapping">generate-mapping</a></li>
        <li><a href="d2r-query">d2r-query</a></li>
        <li><a href="dump-rdf">dump-rdf</a></li>
        <li class="last"><a href="jena">D2RQ + Jena API</a></li>
      </ul>
    </li>
    <li class="group"><span>Support and Development</span>
      <ul>
        <li><a href="https://lists.sourceforge.net/lists/listinfo/d2rq-map-devel">Mailing List</a></li>
        <li><a href="http://github.com/d2rq/d2rq/issues">Issue Tracker</a></li>
        <li class="last"><a href="http://github.com/d2rq/d2rq">GitHub Project</a></li>
      </ul>
    </li>
    <li><a href="resources">Links and Resources</a></li>
    <li><a href="http://www4.wiwiss.fu-berlin.de/is-group/">Live Demo</a></li>
  </ul>
</div>

<div id="main">

<p>The D2RQ Platform is a system for accessing 
  relational databases as virtual, read-only RDF graphs.
  It offers RDF-based access to the content of relational
  databases without having to replicate it into an RDF store.
  Using D2RQ you can:</p>

<ul>
  <li>query a non-RDF database using <a href="http://www.w3.org/TR/sparql11-query/">SPARQL</a></li>
  <li>access the content of the database as <a href="http://en.wikipedia.org/wiki/Linked_Data">Linked Data</a> over the Web</li>
  <li>create custom dumps of the database in RDF formats for loading into an RDF store</li>
  <li>access information in a non-RDF database using the <a href="http://incubator.apache.org/jena/">Apache Jena API</a></li>
</ul>

<p>D2RQ is Open Source software and published under the <a href="http://www.apache.org/licenses/LICENSE-2.0.html">Apache license</a>. The source code is <a href="http://github.com/d2rq/d2rq">available on GitHub</a>. You can contact the dev team on the <a href="https://lists.sourceforge.net/lists/listinfo/d2rq-map-devel">D2RQ mailing list</a> at <a href="mailto:d2rq-map-devel@lists.sourceforge.net">d2rq-map-devel@lists.sourceforge.net</a>.</p>


<h2 id="news">News</h2>

<ul class="news">

<!-- This should have about five items. Move older ones to archive.html -->

<li><strong>Version 0.8.1 released.</strong> This release adds support for W3C's <a href="http://www.w3.org/TR/rdb-direct-mapping/">Direct Mapping</a>, a new <code>d2r-query</code> script for command-line SPARQL querying, a comprehensive set of options for including or excluding specific tables and columns, metadata for each resource and the entire dataset in D2R Server (including <a href="http://www.w3.org/TR/void/">VoID</a> support), an option for specifying SPARQL query timeouts, and D2R Server default settings that work better for large databases. For full details, see the <a href="https://github.com/d2rq/d2rq/blob/9605a30e75be606c022dcd21b11e3b4fc3671cc4/RELEASE_NOTES.md">release notes</a>. <small>2012-06-22</small></li>

<li><strong>Free webinar on D2RQ.</strong> As part of the <a href="http://lod2.eu/">LOD2 project</a>'s series of webinars on Linked Open Data topics, Robert Isele will present a session about D2RQ on Tuesday, April 24th. <a href="https://www2.gotomeeting.com/register/995893370">Sign up here</a>, or see <a href="http://lod2.eu/BlogPost/1119-lod2-webinar-series-linked-data-and-skos-d2r-and-sparqlify.html">here for more information</a>. <small>2012-04-21</small></li>

<li><strong>Poster on D2RQ/Update at WWW2012.</strong> Vadim Eisenberg's <a href="http://d2rqupdate.cs.technion.ac.il/"><em>D2RQ/Update</em> extension</a> will be presented next week in the poster session at the <a href="http://www2012.wwwconference.org/">WWW2012 conference</a> in Lyon, France. See the poster <a href="http://d2rqupdate.cs.technion.ac.il/wpp179-eisenberg.pdf">here</a>. <small>2012-04-13</small></li>

<li><strong>Version 0.8 released.</strong> New features include preliminary SPARQL 1.1 support, Firebird support, generation of RDFS/OWL schemas for databases, and download maps for making the content of CLOB/BLOB columns accessible via HTTP. Datatype compatibility with Oracle, MySQL, SQL Server and HSQLDB has been greatly improved, and a truckload of bugs have been fixed. For full details, see the <a href="https://github.com/d2rq/d2rq/blob/d871bbdde4e0a7ebd96ca66adc76d918cb7548f3/RELEASE_NOTES.md">release notes</a>. <small>2012-03-12</small></li>

</ul>

<p><a href="archive">News archive …</a></p>


<h2 id="overview">Overview and Features</h2>

<p>The D2RQ Platform consists of:</p>
<ul>
  <li>the <strong>D2RQ Mapping Language</strong>, a declarative mapping language 
    for describing the relation between an ontology and an relational data model. 
    <a href="d2rq-language">More…</a>
  </li>
  <li>the <strong>D2RQ Engine</strong>, a plug-in for the Jena Semantic Web toolkit, 
    which uses the mappings to rewrite Jena API calls to SQL queries against the database and passes 
    query results up to the higher layers of the frameworks.</li>
  <li><strong>D2R Server</strong>, an HTTP server that
    provides a Linked Data view, a HTML view for debugging
    and a SPARQL Protocol endpoint over the database.
    <a href="d2r-server">More…</a></li>
</ul>

<p><img src="images/architecture.png" alt="D2RQ Platform architecture diagram" /></p>


<h2 id="compatibility">Database Compatibility</h2>

<dl>
  <dt>Supported databases</dt>
  <dd>Oracle<br />MySQL<br />PostgreSQL<br />SQL Server<br />HSQLDB<br />Interbase/Firebird</dd>
  <dt>ODBC data sources</dt>
  <dd>D2RQ can connect to ODBC data sources like MS Access using an
    ODBC-JDBC bridge. This works with some limitations.
    We recommend using a dedicated JDBC driver for the
    database in question.</dd>
  <dt>Other databases</dt>
  <dd>May or may not work.
    By default, D2RQ interacts with the database using the SQL-92 standard.
    Any compatible database <em>should</em> work out of the box.
    We are interested in reports about D2RQ on other databases.</dd>
</dl>

<p>See <a href="https://github.com/d2rq/d2rq/wiki/Database-Compatibility">Database 
compatibiliy</a> on the D2RQ wiki for more details.</p>


<h2 id="acknowledgements">Acknowledgements</h2>

<div class="logos">
  <a href="http://www.fu-berlin.de/"><img src="images/fu-logo.gif" alt="Freie Universität Berlin logo" /></a><br />
  <a href="http://www.deri.ie/"><img src="images/deri-logo.png" alt="DERI, NUI Galway" /></a>
</div>

<dl class="acknowledgements">
<dt>Maintainers</dt>
<dd>
<a href="http://richard.cyganiak.de/">Richard Cyganiak</a><br />
</dd>
<dt>Project founder</dt>
<dd><a href="http://www.wiwiss.fu-berlin.de/en/institute/pwo/bizer/team/BizerChristian.html">Chris Bizer</a></dd>
<dt>Contributors</dt>
<dd>
<a href="https://github.com/luiseufrasio">Luís Eufrasio Teixeira Neto</a><br />
<a href="http://hannes.muehleisen.org/">Hannes Mühleisen</a><br />
<a href="http://www.deri.ie/about/team/member/aftab_iqbal/">Aftab Iqbal</a><br />
<a href="https://github.com/jgeluk">Jacobus Geluk</a><br />
<a href="https://github.com/melgi">Giovanni Mels</a><br />
<a href="https://github.com/dlvenable">David Venable</a><br />
<a href="http://www.wiwiss.fu-berlin.de/en/institute/pwo/bizer/team/BeckerChristian.html">Christian Becker</a><br />
<a href="http://olafhartig.de/">Olaf Hartig</a><br />
<a href="http://www.langegger.at/">Andreas Langegger</a><br />
Herwig Leimer<br />
<a href="http://surguy.net/">Inigo Surguy</a><br />
<a href="http://www.oliver-maresch.de/">Oliver Maresch</a><br />
Jörg Garbers<br />
</dd>
<dt>Contributing organisations</dt>
<dd><a href="http://www.wiwiss.fu-berlin.de/en/institute/pwo/bizer/">FU Berlin</a>, <a href="http://www.deri.ie/">DERI</a>, <a href="http://www.ucb.com/">UCB</a>, JP Morgan Chase, AGFA Healthcare, HP Labs, Johannes Kepler Universität Linz</dd>
</dl>

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